Custom segment inefficient on transition graph


I have created a custom segment in order to show only the trafic coming from a newsletter campaign (see custom_segment_campaign.png and custom_segment_campaign_result.png).
Even though, the transitions graph show incoming trafic from internal page (see flow_graph.png).
I want to see only the trafic coming from the campaign.

Why is there this internal page section ?
How can I make the result respecting the custom segment ?

Thanks for your help

I think it shows the ‘internal page’ because one visit came from a campaign, and visited the homepage, then visited an internal page and visited the homepage again.